Portable devices, such as cell phones, are becoming increasingly common. These portable devices have grown more complex over time, incorporating many features including, for example, MP3 player capabilities, web browsing capabilities, capabilities of personal digital assistants (PDAs) and the like.
The battery life of these portable devices, however, can be limited. Often, the primary draw of battery power is the display device for these portable devices and, in particular, the backlight, which can be used to illuminate the display device. In many current portable devices, an exemplary process 10 for illuminating the display is shown in FIG. 1. In this process, the backlight is activated (e.g. turned on to generate light) when a user enters a key input into the portable device as shown in operation 12. A timer is started at operation 14 in response to activating the backlight, and the portable device determines, at operation 16, whether a time out of the timer has occurred. If the portable device receives a user key input at operation 18, the timer restarts (in operation 14) and the process continues as described above. If the portable device does not receive a user input while the timer is counting, the time out will occur, and the backlight is deactivated at operation 20.
In addition, users often inadvertently enter key inputs on the input device of the portable device, which can result in the telephone performing operations which the user did not intend. For example, the backlight may illuminate, a telephone number may be dialed, a ring setting may be changed, etc., because the user accidentally contacts a key on the input device. The inadvertent entry of an input is particularly troublesome for a touch screen device, especially one which may receive an inadvertent input when a user has the portable device placed next to the user's ear.